RCA F20536EH CTC146L/LA Not tuning in channel

[jmm83]

Hi
i have a RCA Model F20536EH that uses
chassis CTC146L/LA
from 1992
it was my Grandmothers TV

tv was pretty dirty inside

it had not been powered on in about 12 yrs and worked last time it was unhooked
it had a bunch of Y's on the screen when i first turned it on not sure what that was all about but they went away

it will not tune in ch3 or4 for use with a vcr, converter box ect.
the picture will come on for a second then turn to static.

one way i was able to get a picture was to flip the ch3-4 switch on the back of the vcr when the vcr was on ch4 and the tv on ch3 it has a picture but no sound. but it as sound on a blank fuzzy channel.

i tried re soldering the grounds on the tuner board on the bottom of the main board. maybe i could have missed a few connections?

maybe someone has a whole mainboard for this tv or a tuner
or would there be a way to mod it to use an rca input instead of the tuner?
let me know thanks